Treatment of tobacco



Patented Apr. 15, 1947 TREATMENT OF TOBACCO Alfred J.'Berger and Hoke S. Greene,

Cincinnati, Ohio No Drawing. Application November 28, 1940, Serial No. 367,674

9 Claims.

This invention relates to the processing or treatment of tobacco and has for its object the provision of new methods to improve flavor, color, and other qualities of the tobacco, and to prevent losses resulting from commonly used methods of fermenting tobacco. Generally speaking, the invention provides treatment methods, involving reduced time elements, for achieving uniform results whereby the processing of tobacco is rendered extremely eflicient as compared with older methods wherein both the elements and the results were a matter of uncertainty. More specifically, the invention consists of the process of removing the air, or a part thereof, from moist tobacco in a sealed chamber, and the application of heat, by or under steam pressures substantially greater than atmospheric, for a substantial period of time.

In carrying out our invention, a suitable sealable chamber or vessel may be employed, capable of withstanding high degrees of both vacuum and steam pressure and provided with suitable steam injection and vent means.

Our experiments show that in order to effect an appreciable improvement in the mildness of the tobacco and in the darkness of the color, within a treating time of one-quarter of an hour to three hours, it is necessary to raise the steam pressure in the sealed chamber, after a vacuum has been drawn on moist tobacco, to a value'substantially above atmospheric pressure to insure time of treatment or with the same time involved have produced a still greater degree of mildness in the tobacco, in the following manner. We have drawn a vacuum on the tobacco in the chamber, introduced steam as before until the pressure was substantially above atmospheric, for example -20 pounds gauge, and the temperature of the tobacco increased to approximately 235-260 F.,

' then or shortly thereafter vented some or all of the steam and other gases in excess of atmospheric pressure; then or shortly thereafter again increased the pressure to 10-20 pounds gauge and the temperature to approximately 235-260 F., the excess steam and other gases being then or shortly thereafter vented to the air. Considerable quantities of non-condensible gases are evolved in this process and this washing out of the noncondensible gases and other volatile constituents, which were either adhering to the tobacco or formed from the reactions taking place within the tobacco, tends to speed up the process and has been repeated one or more times.

' A second modification of the procedure just previously described, in which a substantial vacuum has been drawn on the tobacco following each application of steam pressure, has been successfully tried. This modification tends even more to withdraw the non-condensible gases and other volatile constituents from the tobacco.

In additionto all of the above procedures and immediately prior to withdrawing the tobacco that the tobacco reaches a temperature not lower than 220 F. and not higher than 300 F., the said time and temperature factors being in inverse ratio, i. e., the maximum temperature of 300 F.

would be associated with aprocess time of onequarter hour and the temperature of 220 F. would be used for a process time of three hours.

As an example, we have taken two cases of Pennsylvania tobacco, weighing approximately 300 pounds each, sprayed the tobacco with water between each layer of hands in order to increase the moisture content of the tobacco approximately 5 to 8%; placed the cases within the chamber, and subjected them to a vacuum to withdraw all or a part of the air enclosed. Steam was then introduced until the pressure reached 10-20 pounds gauge, and the temperature of the tobacco increased to 235-260 F. This pressure and temperature was held for one hour, then the excess steam and other ases vented to the air and the tobacco removed. The improvement in mildness is very evident to one experienced in judging this quality.

In similar'procedures we have shortened the from the chamber, another vacuum has been 'drawn on the, tobacco for the purpose of with drawing a portion of its. water content and lowering its temperature. This vacuum has been .broken by admitting air or heated gases, then theftobacco was withdrawn from the chamber. With tobacccs in which a darkening of the color as Well as an increase in mildness is desired,'substant-ially the same treatment is employed and experiment indicates the following additional directions. -.The more moist the tobacco before treatment. the darker the shades resulting, all other conditions being equal. Satisfactory-results are obtained with from 25% to moisture content, depending on the type'of tobacco. Some types of tobaccos, less than six to twelve months old, reckoned from time of harvest, may become too tender by use of this high degree of moist heat. Tobaccos may become tender if too high a vacuum is drawn on them before they have reached a pliable condition.

The percentage of moisture of the tobacco will effect the speed of the process. the degree.

suiting. The limits of moisture for successful treatment are not too critical to be described by the customary trade term of good case condition" for tobacco to be darkened. For tobacco to be made more mild, a pliable, that is, a less moist condition is suflicient. Actual percentages of moisture will vary with the types and ages of the tobacco. Dry tobacco in a brittle condition may contain as low "as 9% or as high a 19% moisture. To such dry tobacco moisture may be added by spraying the outside of the hands with water or a solution to. increase its weight about 4% to 9% if it is to be made more mild by this procedure. Such sprayed tobacco may gain an additional 8% to 14% after the steam treatment. The greater the moisture content before steam treatment, the greater will be the gain in moisture. In order to determine the efiectof varied moisture conditions of the tobacco, the previously described experiments were made with unmoistened tobacco, with tobacco sprayed with water, and with tobacco dipped in water or a solution. The greater the moisture content, the

greater the mildness resulting, if all other con- For tobacco to be darkditions are identical. ened, it is usually necessary to case or dip the tobacco in water, or a solution, in order to increase its moisture content sufiiciently to reduce the time of treatment of it to three hours or less.

Similar to chemical reactions, the speed of the process is increasedby increase of the temperature. Temperatures substantially higher than 220 F., are necessary ,to accomplish the desired results in as short a period as three hours. For a tobacco treatment time of one-quarter hour it may be necessary to raise the temperature to 300 F. In order to determine the efiect of a variation of temperatures, the previously described typical experiments were repeated at diiferent maximum temperature ranges as follows: 225-230 F. with a pressure of -6 pounds gauge; 235-240 F. with a pressure between 9 and 10 pounds gauge; 245-250 F. at a corresponding pressure of 14 -15 pounds gauge; and 255-257 F. at a corresponding pressure of -21 pounds gauge. The four cases of tobacco treated in the above manner at a temperature of 225f-230 F. and 5-6 pounds gauge pressure, and at different degrees of moisture, were not appreciably improved in mildness or color. From the experiments at 235 F. up to the higher temperatures the tobacco showed a definite increase.

in mildness and a definite darkening of the color as the temperature was elevated.

Tobacco of difierent types and different crops must be treated by somewhat varied modifications of this process so that limits of treatment cannot be too sharply defined. The three variables which modify the results to the greatest degree are (1) degree of moisture of the tobacco, (2) temperature (usually connected with the steam pressure used) of the tobacco, and (3) length of treatment.

One hour is not a maximum limit for the time treatment even at the temperatures in the neighborhood of 260 F. Tobacco treated in this temperature range (and of different moisture contents) for a period of from two to three hours has been found to be unharmed and even more mild than the single hour .treatment.

Experiments were run with the same crop of 1936 Pennsylvania tobacco at pressures from lbs. gauge to 50 lbs. gauge pressure and corresponding temperatures to as high as 297 F. Again, tobacco of various moisture contents was treated to note the effect of this variable. Also the time of treatment was varied from 5 to 60 minutes. The same relationships between the mildness obtained and length of treatment, the degree of temperature, and the moisture content was found to hold as at the lower ranges, namely, that as each of these was increased separately or in conjunction, the tobacco tended to become more mild. Excellent results were obtained with the lower time limits of approximately one-quarter hour at the higher temperatures of.approximately 300 F. The selection of the optimum conditions depends in a great measure on the character of the crop used.

From the foregoing, it will be seen that the time element is roughly in inverse ratio to the temperature. The varying qualities and types of tobacco treated, as already discussed, render it impracticable to set down with rigid and'mechanical exactitude the ratio in question, but the general rule and the approximate examples given will make the use of the process available to one acquainted with the art.

Chemicals added before or during treatment affect the color of the resulting tobacco as follows: ammonia or other suitable alkaline ma;

terials produce darker shades than water alone;

hydrogen peroxide or other suitable oxidizing substance produce darker shades than water alone; acetic acid or other suitable acidic substances produce lighter shades than water alone; formaldehyde or other suitable reducing substances produce lighter shagies than water alone; assuming all other conditions of the tobacco and the treatment to be identical. Such chemicals have an effect on the taste as well as the color of the tobacco and can be used to modify the flavor of difierent types of tobacco. These chemicals can be added with or without added flavoring substances. They may be readily introduced into the chamber during one of the vacuum periods to avoid extra handling of the tobacco.

In the typical experiments on Pennsylvania tobacco as previously described there was an apparent difference in the results obtained at the lower range up to 240 F., and at 245 F. and higher, indicating a possibility of two separate reactions. The experiments at 240 F. and below, produced tobacco with very little of the so-called sweat or cooked odor. However, with some tobaccos, the degree of mildness obtained at these temperatures, may not be sufficient. Tobacco from the experiments at 245 F. and above, was much more mild, but had this objectionable odor directly on removal from the chamber. Vacuumizing the tobacco in the chamber, or airing it out after removal from the chamber decreased the odor. subjecting the tobacco to acetic acid fumes easily removed all objectionable odor and rendered it sweet smelling and tasting so that it could be used immediately in the manufacture of cigars. A concentration of '7 ounces of glacial acetic acid in a chamber approximately cubic feet capacity containing approximately 600 pounds of tobacco was found satisfactory for this purpose.

The chemical-s used as above described may be added in the form of solutions during the moistening of th tobacco, orif volatile, may be introduced into the chamber during a vacuum period, separately or in conjunction with the steam.

Advantages in the process which we disclose are apparent in the improvement in the mildness of the taste or flavor of the tobacco, in the reduction of the time of treatment, in the uniformity of the darkening of the colors, in the absence of damage due to cellulose-destroying fungi, molds, or bacteria, in the improvement of the burning qualities, and in the fact that the tobacco is sterilized by the process.

It is important to note that our invention discloses conditions that favor the production of darker colors of the tobacco and other sets of conditions that favor a resulting increase of mildness of the tobacco with a minimum of color change.

The various types of tobacco designated by U. s. type 41, 42, 43, 44, 46, 51, 52, 61, and imported Havana were treated successfully in accordance with the present invention and every type tried thus far has been improved.

Our processes make it possible to treat large bulk quantities of tobacco at one time and to achieve a uniform improvement and change throughout all the tobacco in a given bulk. The invention therefore provides for improving the qualities of tobacco and with a maximum efficiency due both to the reduced period of treatment and to the fact of treating large bulked quantities at one time.

It is within the scope of our disclosures to bring about the conditions of treatment by any suitable mechanical means. For example, the steam for heating the tobacco may be introduced into the chamber or may be generated within the enclosure itself. Similarly, the vacuum may be drawn by exhaust pumps, steam ejectors or by condensing steam within the chamber by rapid cooling.

We claim:

1. The process of treating tobacco to improve the color, taste and other qualities thereof, which comprises drawing a, vacuum on moist tobacco in a closed chamber capable of withstanding high pressures, heating the tobacco in contact with steam in the chamber at a. temperature not less than 220 F. and under pressure suflicient to preclude appreciable drying-out of the tobacco, and maintaining these conditions over a continuous .and substantial period of time computed according to the character of the tobacco treated, the time and temperature factors being in inverse ratio and comprised within approximate maximum limits of 3 hours and 300 F., respectively, and approximate minimum limits of one-quarter hour and 220 F., respectively.

2. The process of treating tobacco to improve the color, taste and other qualities thereof, which comprises drawing a. vacuum on moist tobacco in a suitable closed chamber, capable of withstanding high pressures, heating the tobacco in contact with steam to approximately 220-235 F., under pressure suflicient to preclude appreciable drying-out or the tobacco, and maintaining these conditions for a period of approximately one to three hours.

. 3. The process of treating tobacco to improve the color, taste and other qualities thereof, which pressures, heating the tobacco in contact with steam in the chamber at a temperature not less than 220 F. and under pressure sufficient to preclude appreciable drying-out of the tobacco, and maintaining these conditions over a continuous and substantial period of time computed according to the character of the tobacco treated, the time and temperature factors being in inverse ratio and comprised within approximate maximum limits of 3 hours and 300 F., respectively, and approximate minimum limits of one-quarter hour and 220 F., respectively, the tobacco, at the time of the foregoing process, being treated with a conditioning agent to further modify the color and taste characteristics thereof.

5. The process as set forth in claim 4 in which said treating step consists of applyin an alkalizcomprises drawing a vacuum on moist tobacco in a suitable closed chamber, capable of withstanding high pressures, heating the tobacco in contact with steam to approximately 260-300 F., under pressure suflicient to preclude appreciable drying-out of the tobacco, and maintaining these conditions for a period of approximately one-quarter to one hour.

4. The process of treating tobacco to improve the color, taste and other qualities thereof, which comprises drawing a vacuum on moist tobacco in a closed chamber capable of withstanding high ing agent to the tobacco during said process.

6. The process as set forth in claim 4 in which said treating step consists of applying a reducing agent to the tobacco during said process.

7. The process as set forth in claim 4 in which said treating step consists of applying an acidifying agent to the tobacco during said process.

8. The process of treating tobacco which consists in drawing a vacuum on moist tobacco in a closed chamber capable of withstanding high pressures, heating the tobacco in contact with steam in the chamber at a temperature of not less than 220 F. and under a pressure suflicient to preclude appreciable drying-out of the tobacco, and maintaining these conditions over a continuous and substantial period of time computed according to the character of the partially cured tobacco treated, the time and temperature factors being in inverse ratio and comprised within approximate time limits of one-quarter to three hours and approximate temperature limits of 220 F. to 300 F.

9. The process of treating tobacco to improve the color, taste and other qualities thereof, which comprises drawing a vacuum on moist tobacco in a closed chamber, capable of withstanding high pressures, heating the tobacco in contact with steam to approximately 235-260 F., under pressure sufficient to preclude appreciable drying-out of the tobacco, and maintaining these condi tions for a period of approximately one hour.

ALFRED J. BERGER. HOKE S. GREENE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 273,362 Howard Mar. 6, 1883 1,843,304 Scalvini Feb. 2, 1932 877,698 Bedortha. Jan. 28, 1908 1,437,095 Delling Nov. 28, 1922 2,086,194 Smith July 6, 1937 2,217,931 McCorkhill Oct. 15, 1940 2,164,030 Coe June 27, 1939 FOREIGN PATENTS Number Country Date 84,290 Austrian June 10, 1921 2,394 British 1915 226,847 British Dec. 31, 1924 OTHER REFERENCES Carpenter and Diederiche, Experimental En gineering. Figure 245 (following page 338), Seventh edition, 1911. (Copy in Division 2.) 

